STORAGE OF HYDROGEN IN SINGLE-WALLED CARBON NANOTUBES

Pores of molecular dimensions can adsorb large quantities of gases owi ng to the enhanced density of the adsorbed material inside the pores(1 ), a consequence of the attractive potential of the pore walls, Peders on and Broughton have suggested(2) that carbon nanotubes, which have d iameters of typically a few nanometres, should be able to draw up liqu ids by capillarity, and this effect has been seen for low-surface-tens ion liquids in large-diameter, multi-walled nanotubes(3). Here we show that a gas can condense to high density inside narrow, single-walled nanotubes (SWNTs), Temperature-programmed desorption spectrosocopy sho ws that hydrogen will condense inside SWNTs under conditions that do n ot induce adsorption within a standard mesoporous activated carbon, Th e very high hydrogen uptake in these materials suggests that they migh t be effective as a hydrogen-storage material for fuel-cell electric v ehicles.